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Biomedical subjects

J A Hamilton

Publications and source records attributed to J A Hamilton.

At least 91 records · Page 5Linked to original sources
PubMed1997

Granulocyte-macrophage colony stimulating factor exacerbates collagen induced arthritis in mice.

OBJECTIVE: To examine the effect of granulocyte-macrophage colony stimulating factor (GM-CSF) on disease progression in the collagen induced arthritis (CIA) model in mice. METHODS: DBA/1 mice were primed for a suboptimal CIA response by intradermal injection of chick type II collagen without a secondary immunisation. Three weeks after immunisation the mice were given four to five consecutive daily intraperitoneal injections of recombinant murine GM-CSF (15 micrograms; 5 x 10(5) U), or vehicle, and arthritis development was monitored by clinical scoring of paws and calliper measurements of footpad swelling. At approximately six to eight weeks after immunisation mice were killed, their limbs removed and processed for histological analyses of joint pathology. RESULTS: Control animals receiving a single immunisation with collagen exhibited a varied CIA response both in terms of incidence and severity. Mice treated with GM-CSF at 20 to 25 days after immunisation with collagen had a consistently greater incidence and more rapid onset of disease than the vehicle treated control mice, based on clinical assessment. GM-CSF treated mice showed higher average clinical scores and greater paw swelling than controls. Histological analyses of joints reflected the clinical scores with GM-CSF treated mice displaying more pronounced pathology (synovitis, pannus formation, cartilage and bone damage) than control mice. CONCLUSION: GM-CSF is a potent accelerator of the pathological events leading to chronic inflammatory polyarthritis in murine CIA supporting the notion that GM-CSF may play a part in inflammatory polyarthritis, such as rheumatoid arthritis.

Animals↗
PubMed1997

Identification of PRG1, a novel progestin-responsive gene with sequence homology to 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

To define early molecular targets of progestin action, the differential display technique was used to identify genes with altered levels of expression in T-47D breast cancer cells treated with the synthetic progestin ORG 2058 for 3 h. PRG1 was first isolated as a 200-bp cDNA clone and its progestin regulation confirmed by Northern analysis. Cloning of the complete coding region of PRG1 revealed that it shared a high degree of amino acid sequence identity with isoforms of the enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase from several tissues and species. Expression of PRG1 mRNA was observed in several normal breast epithelial and breast cancer cell lines and in a variety of human tissues, with highest expression in the breast, aorta, and brain. In T-47D cells, PRG1 mRNA was rapidly and transiently induced by progestins, expression peaking between 2 and 4 h and returning to control levels by 12 h. Progestin-induced increases in PRG1 mRNA were inhibited by the progestin antagonist RU 486 and occurred via the progesterone receptor. Progestin induction of PRG1 mRNA was also inhibited by actinomycin D but not by cycloheximide. PRG1 is therefore a novel human gene that is directly regulated by progestins via the progesterone receptor.

Amino Acid Sequence↗
PubMed1996

Requirement for Y706 of the murine (or Y708 of the human) CSF-1 receptor for STAT1 activation in response to CSF-1.

Using FDC-P1 derived cell lines which ectopically express either the wild type or mutant forms of the murine CSF-1 receptor in which individual tyrosine residues have been replaced with phenylalanine, we analysed the requirement for tyrosine residues of the receptor for the activation of STAT proteins in response to CSF-1. We found Y706 to be required for efficient activation of STAT1. The activation of STAT3 was not affected by the mutation of Y706 to phenylalanine. The addition of phosphopeptides spanning Y708 of the human CSF-1 receptor (identical with the sequence surrounding Y706 of the murine receptor) to electrophoretic mobility shift assays led to competition of the formation of STAT1 containing complexes, SIF-B and SIF-C with the DNA probe. These phosphopeptides did, however, not affect the formation of the STAT3 containing complex, SIF-A, with the probe. Replacement of Y807 with phenylalanine led to a complete block of activation of all STAT proteins in response to CSF-1, however, this phosphotyrosine does not appear to represent a STAT binding site of the receptor as a phosphopeptide spanning Y809 of the human CSF-1 receptor could not compete any STAT/DNA complex formation in electrophoretic mobility shift assays.

Animals↗
PubMed1996

Dissociation of long and very long chain fatty acids from phospholipid bilayers.

Dissociation of fatty acids (FA) from and transbilayer movement (flip-flop) in small unilamellar phosphatidylcholine vesicles (SUV) were monitored by measuring the pH inside the vesicle with an entrapped water-soluble fluorophore, pyranin. With a pH gradient imposed upon SUV preloaded with FA, the rate of flip-flop of saturated very long chain FA (C20:0, C:22:0, and C24:0) was shown to be fast (t1/2 < 1 s); previously, we showed by stopped flow measurements that flip-flop of long chain (14-18 carbons) FA is very fast [t1/2 < 10 ms; Kamp, F., et al. (1995) Biochemistry 34, 11928-11937]. The rates of dissociation of FA from SUV were evaluated by incorporating FA into donor vesicles and measuring transfer to acceptor vesicles. The transfer was followed by changes in internal pH of either donor or acceptor vesicles with stopped flow (C14:0, C16:0, C17:0, C18:0, C18:1, and C18:2) or on-line (C20:0, C22:0, and C24:0) fluorescence. All FA showed a single-exponential transfer process that was slower than the lower limits established for the rate of flip-flop, with t1/2 of dissociation ranging from 20 ms for C14:0 to 1900 s for C24:0. The pseudo-unimolecular rate constant (koff) for dissociation of C14:0 to C26:0 showed a 10-fold decrease for each addition of two CH2 groups to the acyl chain and a delta (delta G) of -740 cal/CH2. The dissociation rate constants for oleic acid (18:1) and linoleic acid (18:2) were 5 and 10 times faster, respectively, than that of C18:0. The rates of dissociation for typical dietary FA are sufficiently rapid that complex mechanisms (e.g. protein-mediated) may not be required for their desorption from biological membranes. The very slow dissociation rates for C24:0 and C26:0 may accentuate their pathological effects in diseases in which they accumulate in tissues.

Arylsulfonates↗
PubMed1996

Differences in the kinetics of activation of protein kinases and extracellular signal-related protein kinase 1 in colony-stimulating factor 1-stimulated and lipopolysaccharide-stimulated macrophages.

To determine the relevance of mitogen-activated protein kinase activity to macrophage proliferation, we measured the stimulation of myelin basic protein (MBP) kinase and extracellular signal-related protein kinase (ERK) activity in a macrophage cell line (BAC1.2F5), bone marrow-derived macrophages (BMM) and resident peritoneal macrophages (RPM). By using an 'ingel' MBP kinase assay the activities of renaturable MBP kinases were detected, including several with molecular masses similar to those of ERK-1 and ERK-2. These represented a minor fraction of total activity and were not activated to an appreciable extent by colony-stimulating factor 1 (CSF-1). By using a sensitive and specific immune-complex kinase assay, activation of ERK-1 by CSF-1 and lipopolysaccharide (LPS) was demonstrated. Two kinetically distinct pathways of ERK-1 activation by CSF-1 were resolved, with peak activations occurring at 5 and 15 min. The kinetics and degree of activation were similar in BMM, BAC1.2F5 cells and RPM. LPS activated ERK-1 with a single peak at 10-15 min, corresponding to the later peak of activation by CSF-1. Thus there was no strict correlation between ERK activation and macrophage proliferation.

Animals↗
PubMed1996

Association between phosphatidylinositol-3 kinase, Cbl and other tyrosine phosphorylated proteins in colony-stimulating factor-1-stimulated macrophages.

Colony stimulating factor-1 (CSF-1) stimulation of the macrophage cell line BAC1.2F5 and murine bone marrow-derived macrophages resulted in tyrosine phosphorylation of phosphatidylinositol-3 kinase (PI-3 kinase) p85 alpha and its stable association with several tyrosine phosphorylated proteins, including CSF-1 receptor (p165), p120, p95 and p55-p60. p120 co-migrated with the product of the protooncogene c-cb1 in anti-p85 alpha immunoprecipitates, and associated with p85 alpha in a rapid and transient manner. Reciprocal experiments confirmed the presence of p85 alpha in anti-Cb1 immunoprecipitates on CSF-1 stimulation of macrophages. PI-3 kinase immunoprecipitates from the myeloid FDC-P1 cell line expressing mutant CSF-1 receptor (Y721F), which does not associate with PI-3 kinase, still contained Cbl. The identity of the tyrosine phosphorylated protein p95 remains unknown. The interaction between p85 alpha and the tyrosine phosphorylated proteins survived anion-exchange chromatography, suggesting perhaps the presence of a stable complex; furthermore, in CSF-1-treated BAC1.2F5 cell extracts, only one of the two pools of PI-3 kinase separated by chromatography was present in this putative complex. The association did not appear to correlate with proliferation, since a similar interaction between p85 alpha and tyrosine phosphorylated proteins was also observed in poorly proliferating resident peritoneal macrophages stimulated with CSF-1. The possible significance of these findings for CSF-1-regulated macrophage functions is discussed.

Animals↗
PubMed1996

Intracellular pH in adipocytes: effects of free fatty acid diffusion across the plasma membrane, lipolytic agonists, and insulin.

The main function of white adipose tissue is to store nutrient energy in the form of triglycerides. The mechanism by which free fatty acids (FFA) move into and out of the adipocyte has not been resolved. We show here that changes in intracellular pH (pH1) in adipocytes correlate with the movement of FFA across cellular membranes as predicted by the Kamp and Hamilton model of passive diffusion of FFA. Exposure of fat cells to lipolytic agents or external FFA results is a rapid intracellular acidification that is reversed by metabolism of the FFA or its removal by albumin. In contrast, insulin causes an alkalinization of the cell, consistent with its main function to promote esterification. Inhibition of Na+/H+ exchange in adipocytes does not prevent the changes in pHi caused by FFA, lipolytic agents, or insulin. A fatty acid dimer, which diffuses into the cell but is not metabolized, causes an irreversible acidification. Taken together, the data suggest that changes in pHi occur in adipocytes in response to the passive diffusion of un-ionized FFA (flip-flop) into and out of the cell and in response to their metabolism and production within the cell. These changes in pHi may, in turn, modulate hormonal signaling and metabolism with significant impact on cell function.

Adipocytes↗
PubMed1996

Differential regulation of cell cycle machinery by various antiproliferative agents is linked to macrophage arrest at distinct G1 checkpoints.

There is currently much interest in the mechanisms of action of antiproliferative agents and their effects on cell cycle machinery. In the present study we examined the mechanisms of action of four unrelated agents known to inhibit proliferation of CSF-1-stimulated bone marrow-derived macrophages (BMM). We report that 8-bromo-cAMP (8Br-cAMP) and lipopolysaccharide (LPS) potently reduced CSF-1-stimulated cyclin D1 protein, and cyclin-dependent kinase (cdk) 4 mRNA and protein levels, while the inhibitory effects of the Na+/ H+ antiport inhibitor 5-(N',N'-dimethyl) amiloride (DMA) and interferon gamma (IFN gamma ) were only weak. All agents repressed CSF-1-stimulated retinoblastoma protein phosphorylation. Furthermore, 8Br-cAMP and to a lesser extent IFN gamma, also reduced CSF-1-stimulated levels of E2F DNA binding activity in a macrophage cell line, BAC1.2F5. An explanation for the different effects of the agents is that 8Br-cAMP and LPS were found to arrest BMM in early/mid-G1, while IFN gamma and DMA arrested cells in late G1 or early S phase. These data indicate that (1) different antiproliferative agents can arrest the same cell type at distinct checkpoints in G1 and (2) effects of antiproliferative agents on cell cycle machinery is linked to the position at which they arrest cells in G1.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Extracellular mutations of non-obese diabetic mouse FcgammaRI modify surface expression and ligand binding.

The non-obese diabetic mouse (NOD) expresses a unique form of the high affinity receptor for IgG (FcgammaRI), containing multiple mutations that result in substitutions and insertions of amino acids and a truncated cytoplasmic tail. As a result of these major changes, receptor affinity for IgG increases 10-fold over that of wild-type FcgammaRI from BALB/c mice, while the specificity for ligand is retained. Kinetic analysis revealed that while the association rate of IgG with FcgammaRI from NOD mice (FcgammaRI-NOD) and FcgammaRI from BALB/c mice (FcgammaRI-BALB) is similar, IgG bound much more tightly to FcgammaRI-NOD as revealed by a profoundly diminished dissociation rate. Transfection studies demonstrated that FcgammaRI-NOD was expressed at one-tenth of the level of FcgammaRI-BALB. Although mouse FcgammaRI was previously not known to associate with the FcepsilonRI gamma-subunit, transfection of COS-7 cells demonstrates that like human FcgammaRI, mouse FcgammaRI is also able to associate with this signaling subunit. Furthermore, expression levels of FcgammaRI-NOD were not restored by the presence of the FcepsilonRI gamma-subunit. The difference in the levels of expression was mapped to mutations in the extracellular region of FcgammaRI-NOD as replacement of the extracellular domains with those of human FcgammaRI or FcgammaRI-BALB restored expression to that of human FcgammaRI or FcgammaRI-BALB.

Amino Acid Sequence↗
PubMed1996

Flexibility is a likely determinant of binding specificity in the case of ileal lipid binding protein.

BACKGROUND: The family of lipid binding proteins (LBPs) includes a large number of fatty acid binding proteins (FABPs) but only two proteins (ileal lipid binding protein, ILBP, and liver fatty acid binding protein) that can bind both fatty acids and bile acids. Bile acid transport is medically and pharmacologically important, but is poorly understood. To understand the binding properties of ILBP, we studied its solution structure with and without bound lipids and compared these with known structures of FABPs. RESULTS: The sequence-specific 1H resonance assignments for porcine ILBP have been determined by homonuclear two-dimensional (2D) NMR spectroscopy for the apo-protein as well as for ILBP complexes with fatty acid and bile acid ligands. From NOE spectra and hydrogen exchange data, similar secondary structure elements were identified for all three protein forms. ILBP is composed of ten antiparallel beta strands arranged in two nearly orthogonal beta sheets (a fold seen in other FABPs, and dubbed the "beta-clam shell'), covered on one side by two short, nearly parallel alpha helices. Binding of fatty acids or bile acids to ILBP alters mainly the side-chain proton resonances of amino acids within the protein cavity, indicating that both bile acids and fatty acids can bind in the interior of the protein between the two beta sheets; binding of bile acids stabilizes the protein backbone by a small amount. Fast hydrogen exchange rates for the backbone amide protons of ILBP indicate that the hydrogen-bonding network of the beta sheet in ILBP is weaker than the corresponding network in rat intestinal and bovine heart FABPs. CONCLUSIONS: The tertiary structure of ILBP is similar to that of other LBPs, but appears to be unusually flexible, with a relatively weak hydrogen-bonding network. It is likely that this flexibility is important in allowing bile acids, which are larger and more rigid than fatty acids, to enter the central cavity of the protein.

Amino Acid Sequence↗
PubMed1996

Endogenous IFN-alpha beta suppresses colony-stimulating factor (CSF)-1-stimulated macrophage DNA synthesis and mediates inhibitory effects of lipopolysaccharide and TNF-alpha.

Murine bone marrow-derived macrophages (BMM) are widely used as a suitable model to study the proliferative response to macrophage-CSF or CSF-1. We report here that the amount of DNA synthesis observed in BMM cultures in response to CSF-1 can be masked quite significantly by low levels of IFN-alpha beta produced in the cultures. It was found that Ab to IFN-alpha beta could enhance the proliferative response in CSF-treated BMM that were able to respond to endogenous IFN-alpha beta; however, BMM from mice lacking a component of the type I IFN receptor did not show any enhancement of CSF-1-dependent DNA synthesis on addition of the Ab. While DNA synthesis in CSF-1-stimulated BMM from normal mice was also very sensitive to the inhibitory actions of very low concentrations of added IFN-alpha beta, DNA synthesis in BMM from the "knockout" mice was not, indicating that the type I IFN receptor component containing the null mutation was essential for signal transduction. Previously it was shown that bacterial LPS, TNF-alpha, IFN-gamma, and cAMP could all inhibit CSF-1-stimulated BMM DNA synthesis and proliferation. Using the combined approach of blocking IFN-alpha beta Ab and the IFN receptor "knockout" mice, it was found here that the growth-inhibitory effects of LPS and TNF-alpha are due, to a significant extent, to endogenous IFN-alpha beta, whereas those of IFN-gamma and cAMP occur by a different mechanism. it is proposed that the type I IFN receptor (IFNAR 1) "knockout" mice may be useful in delineating some of the in vivo actions of CSF-1, LPS, TNF-alpha, and possibly other agents.

Animals↗
PubMed1996

c-fos antisense DNA inhibits proliferation of osteoclast progenitors in osteoclast development but not macrophage differentiation in vitro.

We previously reported that osteoclast formation in vitro, by coculture of mouse bone marrow and primary osteoblastic cells, occurs in two phases: proliferation of osteoclast progenitors followed by terminal differentiation into mature osteoclasts. Using this coculture system, we examined the effects of c-fos antisense and sense phosphorothioate oligonucleotides on osteoclast development and macrophage differentiation. Treatment with c-fos antisense for the first 4 days of coculture inhibited osteoclast formation in a dose-dependent fashion. However, when c-fos antisense was added during the second phase of coculture (4-6 days), osteoclast formation was unaffected. In contrast, c-fos antisense treatment had no effect on the appearance of F4/80 antigen-positive cells of the macrophage lineage in these cultures or on the induction by colony stimulating factor-1 of macrophage colony formation in cultures of mouse bone marrow cells in agar. Neither osteoclast differentiation nor macrophage appearance was inhibited by adding control c-fos sense in the cocultures. When c-fos antisense was added into an assay of bone resorption by mature osteoclasts, pit formation on dentine slices was unaffected. These results indicate that c-fos plays an important role in the proliferative phase of osteoclast progenitors in osteoclast development, but not in the terminal differentiation phase or in the bone resorbing activity of mature osteoclasts. c-fos antisense specifically inhibited osteoclast formation but had no effect on macrophage development.

Analysis of Variance↗
PubMed1996

13C MAS NMR studies of crystalline cholesterol and lipid mixtures modeling atherosclerotic plaques.

Cholesterol and cholesteryl esters are the predominant lipids of atherosclerotic plaques. To provide fundamental data for the quantitative study of plaque lipids in situ, crystalline cholesterol (CHOL) and CHOL/cholesteryl ester (CE) mixtures with other lipids were studied by solid-state nuclear magnetic resonance with magic-angle-sample spinning. Highly distinctive spectra for three different crystalline structures of CHOL were obtained. When CHOL crystals were mixed with isotropic CE oil, solubilized CHOL (approximately 13 mol % CHOL) was detected by characteristic resonances such as C5, C6, and C3; the excess crystalline CHOL (either anhydrous or monohydrate) remained in its original crystalline structure, without being affected by the coexisting CE. By use of 13C-enriched CHOL, the solubility of CHOL in the CE liquid-crystalline phase (approximately 8 mol %) was measured. When phosphatidylcholine was hydrated in presence of CHOL and CE, magic-angle-sampling nuclear magnetic resonance revealed liquid-crystalline CHOL/phosphatidylcholine multilayers with approximately an equal molar ratio of CHOL/phosphatidylcholine. Excess CHOL existed in the monohydrate crystalline form, and CE in separate oil or crystalline phases, depending on the temperature. The magic-angle-sampling nuclear magnetic resonance protocol for identifying different lipid phases was applied to intact (ex vivo) atherosclerotic plaques of cholesterol-fed rabbits. Liquid, liquid-crystalline, and solid phases of CE were characterized.

Animals↗
PubMed1996

Granulocyte colony-stimulating factor-stimulated proliferation of myeloid cells: mode of cell cycle control by a range of inhibitors.

The myeloid cell line, NFS-60, is dependent on granulocyte colony-stimulating factor (G-CSF) or interleukin-3 (IL-3) for survival and growth. Long-term G-CSF-dependent proliferation was found to be completely inhibited by interferon-gamma (IFN-gamma), cyclic AMP, and dimethylamiloride and partially inhibited by IFN-alpha and lipopolysaccharide. With the exception of IFN-gamma, these agents exhibited a corresponding pattern of inhibition of DNA synthesis in quiescent NFS-60 cells stimulated with G-CSF. IFN-gamma was only a weak inhibitor of DNA synthesis, suggesting that it may act at a later stage to block proliferation. The addition of G-CSF to NFS-60 cells resulted in phosphorylation of the retinoblastoma protein (pRB) and activation of E2F DNA binding activity. The inhibitors were found to suppress the phosphorylation of pRB, lead to the production of higher order E2F complexes, and suppress the expression of c-myc and proliferating cell nuclear antigen (PCNA) to an extent that correlated with their ability to block DNA synthesis. These findings are consistent with the notion that the ratio of free/bound E2F binding activity is critical in controlling cell cycle progression through G1 to S-phase in these cells.

Amiloride↗
PubMed1996

Aberrant activation of JAK/STAT pathway components in response to G-CSF, interferon-alpha/beta and interferon-gamma in NFS-60 cells.

There is evidence that the cellular responses to cytokines, such as granulocyte colony stimulating factor (G-CSF) and interferons, depend on prior activation of components of the JAK/STAT signalling pathway. We report here that the myeloid cell line NFS-60 shows aberrant JAK/STAT signalling yet elicits expected biological responses to G-CSF and interferons-alpha/beta and gamma. Instead of increased phosphorylation of JAK1 and JAK2 in response to G-CSF and interferon-gamma, and JAK1 and Tyk2 in response to interferon-alpha/beta, we observed only an increase of phosphorylation of Tyk2 in response to all of these cytokines in NFS-60 cells. The subset of STAT proteins being activated in response to these cytokines was unusual as well. G-CSF activated STAT3 and STAT5A, whereas interferons activated, in addition to STAT1 and STAT5 other, as yet unidentified, DNA binding proteins. However, NFS-60 cells show normal biological responses to these cytokines, such as proliferation in response to G-CSF, and reduction of proliferation, induction of an anti-viral response and induction of specific genes in response to interferons.

Animals↗
PubMed1996

Monoacylglycerols alter the lipid composition and molecular mobility of phosphatidylcholine bilayers: 13C NMR evidence of dynamic lipid remodeling.

The physical effects of monoacylglycerols (MAG) in small unilamellar vesicles composed of phosphatidyl-choline (PC), triolein, cholesterol, and varying amounts of monopalmitin and monoolein were studied by 13C-NMR. The signal to noise ratio of the carbonyls of PC and triolein were enhanced by the addition of 1,2-di-[1-13C]palmitoylphosphatidylcholine and tri-[1-13C]oleoylglycerol. The linewidths of the carbonyl-13C, choline methyl, olefinic carbon, and terminal methyl resonances were measured digitally from vesicles with 0 to 42 mol % of MAG. Significant increases in the linewidth of carbonyl (P < 0.05), olefinic and terminal methyl carbons (P < 0.01) of vesicles containing 42 mol % monopalmitin indicated that these groups experienced restricted molecular mobility at high monopalmitin concentrations. However, more striking was the apparent displacement of triolein from the surface environment of PC bilayers to an oil-like environment in systems containing only 8 mol % monopalmitin. Displacement of triolein from the surface by monoolein occurred only above 15 mol %. Thus, saturated and monounsaturated monoacylglycerols, natural products of lipoprotein metabolism, dynamically alter both the lipid composition and molecular mobility of lipoprotein surfaces in distinct ways.

Chemical Phenomena↗
PubMed1996

Incorporation of medium chain triacylglycerols into phospholipid bilayers: effect of long chain triacylglycerols, cholesterol, and cholesteryl esters.

The ability of water-insoluble molecules such as triacylglycerols to partition from oil phases into phospholipid interfaces may be crucial to their hydrolysis by lipases in the aqueous environment of plasma and cells. This study uses high resolution and magic angle spinning 13C NMR spectros-copy to measure the solubility of the 8-carbon medium chain triacylglycerol, trioctanoin, in the lamellar structure of phospholipids (vesicles and multilayers) in the presence of other neutral lipids that may compete for an interfacial location (long chain triacylglycerol, cholesteryl ester, and cholesterol). In the presence of a saturating concentration of triolein (approximately 3 mole%), the solubility of trioctanoin in egg phosphatidylcholine vesicles decreased from 10 mole% to 7 mole%. The presence of a saturating concentration of trioctanoin (approximately 10 mole%) decreased the interfacial solubility of long chain triolein to approximately 1 mole%. Cholesteryl oleate in phospholipid vesicles slightly diminished the incorporation of trioctanoin into the surface. The presence of cholesterol reduced the interfacial solubility of trioctanoin, but at a high level of cholesterol (30 mole%), trioctanoin had a solubility of 3 mole%. Thus, even in the presence of other competing neutral lipids, medium chain triacylglycerol retains a favorable location and surface concentration for efficient hydrolysis. 13C NMR analysis thus provides an explanation for preferential hydrolysis of medium, compared to long chain triacylglycerol, in a physical blend of medium and long chain triacylglycerol in a single emulsion particle, and in general, a valuable approach to determine substrate availability at phospholipid surfaces.

Caprylates↗